I recently read The Angry DM's Thy Game Mastering Commandments, in which he recommends establishing (and presenting for players to see) a "GM Credo," a set of principles you aim to adhere to when running games. Given that my game-mastering philosophy has been undergoing some evolution (or at least examination) lately, I think this would be a useful exercise.

Some caveats up front: my game-mastering philosophies have morphed and occasionally completely reversed over the years. Sometimes I was experimenting, sometimes I was operating in another set of circumstances that made sense at the time, and sometimes I was flat out wrong about something. This is a statement of my GMing principles as of today, and moving forward. As with any set of ideals, I might not always live up to it, but I am at least going to try.

Some of this stuff is pretty basic, too, but hey, I might as well be thorough.

Specific trumps general.

For instance, if we are playing a game where your party are members of an organization and given assignments, that supersedes the usual principles of providing multiple hooks.

The rules provide a framework for interacting with the game world. The "book" (whatever book that may be) is the baseline, and any variations from that baseline (i.e., "house rules") will be made clear before a player is required to make a decision.

I will use game systems that use the minimum possible complexity for the desired effect.

A game system that cannot easily be played without computer assistance (or at most a pocket calculator), is an undesirable game system. I didn't realize just how sick I was of 3.x/PF until I started messing with 5E.

As referee, my job is to understand the rules, and to interpret them when there is ambiguity. Rulings at the table will be treated as house rules going forward.

House rules are always subject to evaluation and debate between sessions. During a session, if we can't come to an agreement within a few minutes, I'll pick a ruling and go on, subject to debate later.

When I present a game to the group, it is a proposal, not a dictum.

Until we've all agreed to a campaign premise and its attendant house rules, it's up for modification or veto. There's no point in trying to run a game we don't all want to play. If as time goes on, the campaign evolves, or the players would like to take it in another direction, that's fine, as long as we're all on the same page about it.

I will do my best to run the game the players want to play.

Of course, you have to let me know what that is. I am occasionally shocked to find out there's something that's been bugging someone for ages and I had no idea. The whole point of the item above is that we should all be expecting more or less the same thing out of a game. Also, keep in mind that as the GM, I'm one of the players too. I can't run a game I hate!

It's okay to take the game seriously.

It's also okay to not take the game seriously. The important thing is knowing when to do which. I will always try to create a coherent world that operates by a recognizable set of rules, but those rules will vary from world to world. The spooks in Ghostbusters are going to have a different level of "seriousness" from a cursed wraith in Dungeons & Dragons.

I am running for the group, not for any individual player.

If this means saying, "Okay, that character goes off on their own adventure, please create a new character who will work with the group," so be it. I will not start a session until the group has established a reason why the team exists and will work together. This can be as simple as "We are friends and want to go exploring" or "I own a ship and hired these guys to be my crew."

I will present multiple hooks that are reasonably easy to find. Player characters can always say "no."

I will not take away players' freedom of choice without their consent. Joining a campaign in which you are given a mission at the start of each adventure means that you have agreed to accept and attempt to perform said missions from the start– or at the very least, refusing a given mission would represent a major event within the campaign framework.

Hooks are there to provide some kind of structure beyond "You are here, and here's a map, what do you do?" They are designed to help avoid "decision paralysis" and give you something to work with. They are not there to proclaim, "There's the plot, go get it!" and then punish you if you don't.

The issue of multiple hooks is also a matter of player choice: if you are completely free to do anything you want (as long it's follow the only hook presented), you aren't really free, are you? The consequences of following/not following one hook over another might be more or less desirable to your character– that's just the way the world works. But I have failed in my role as an impartial referee if there is a "right" or "wrong" answer to the question of "What do you do?"

Some players "build" a character; some "discover" the character through play. Therefore, I will not require back-stories, disadvantages, or similar character flags to begin the game.

(Names are still necessary for all characters, however. You are not playing chess pawns.) Be aware that this may leave your character seriously "underpowered" if the game system selected for a campaign builds such things into character creation (e.g., Savage Worlds). If all else fails, you could always use the 5E method and roll dice to pick something!

For those players who enjoy it, I will do my best to provide opportunities for your characters to pursue their own goals, tie their back-stories into the broader campaign, and so forth.

Again, this assumes that you let me know what those are. This is my favorite part of roleplaying games, so obviously for me the more the better; but it's not everybody's thing, and I don't want it to be a requirement for participation the game.

I don't know how any given scenario will end, and I have at best an educated guess about how the middle will go.

I will create scenarios, not scenes. Scripted events ("if player kills cult leader while he's chanting, summoned monster will go berserk") may occur, but I will not force their appearance ("no matter how long it takes the players to get to the summoning chamber, the priest will be just about to finish his chant"). A scripted in medias res moment might be used to kickstart a campaign or a session, as appropriate for the campaign, but those will not be done in a way that takes away the players' freedom of choice, as described earlier.

I will not create "guessing game" situations.

This doesn't mean that I'll telegraph the result of relatively minor choices ("turn right or left at the end of the hall"); what this does mean is that you will always either have the information you need to make an important choice, or knowing that you lack information, you'll be able to get it (even if that's by asking me directly). (Of course, if asked directly, I may answer with, "Perhaps you should look for clues." That's part of gaming, after all!) If you ever feel like a life-or-death decision might as well be the flip of a coin, I've done something wrong.

NPCs are speaking for themselves; they are not the GM wearing a mask.

Like most humans, most NPCs are relatively honest, but there's always the chance they may be wrong, they may be lying, or they may simply be making noise. But I'm not going to use NPCs to send you messages. As the GM, it's my job to play "the rest of the world" based on what those people would do. If the barbarian hireling says "I'm bored, let's go kill something," it's because the barbarian hireling is bored, not because I want to goad you into a fight scene.

I will not allow players to wander into deadly peril without warning.

If players choose to put themselves in deadly peril, I will not shield them from it, either. Note that going to an adventure site (however that may be defined for the game at hand) is by default "being in deadly peril" unless you have reason to believe otherwise. In a combat situation, the opposition will be playing to win.

I will roll dice in the open.

I used to be a big ol' fudger; I have since come to the conclusion that far from "making the game more fun," this actually hurts the game in the long run, because the players can never know if they overcame a challenge on their own merits, or because the referee was "home cooking." This in turn leads to the assumption that the PCs will win or lose due to GM predestination, which puts me right back in the role of having "written" the story before the players ever get to the table.

If there is a choice between the players rolling dice, or NPCs/monsters rolling dice, the players will roll the dice.

This may give the players metagame knowledge their characters could not reasonably have; I will trust the players not to abuse this.

For example, in our most recent session, the owlbear that mauled Gimlet rolled a supremely high Stealth check against your characters' passive Perception scores. This is how the rules are designed, but the net result was "Bang! You're (almost) dead without warning and can't do anything about it!" for Josh. Even though this was using the rules as written, it removes the player's freedom, which is something I don't want to do.

How I would handle that same situation now, were it to come up again, would be to say, "An owlbear has been stalking your party through the forest for an hour, and is closing in for the kill. Everyone make a Perception check against its Stealth to avoid surprise." Given how well the owlbear rolled, the net result of the fight may have very well been the same, but it would at least have made you active participants instead of simply receiving a bucket of damage out of the blue.

I will not show you things you can't have, although it may require effort to acquire it.

This is something I have only been peripherally aware of until recent discussions, but an artifact of the 3.x/PF system and its "magic economy" is that there are shops full of super-wifty magic items, that you'll never be able to afford. The idea is supposed to be that you'll be inspired to go out and find treasure to get these things (and to restrict access to them until such time as they wouldn't completely unbalance the game), but due to the "wealth-by-level guidelines," the likelihood of finding the piles of money you'd need in any given adventure is vanishingly low.

I agree, that sucks. As a player, it has certainly frustrated me that I wanted Obsidian to be making use of her tricked-out Use Magic Device skill, only to be thwarted by the fact that there aren't any magic devices for her to use. And as a GM, I intend to find a way to keep this from happening in my games in the future. In more traditional D&D settings this is as simple as removing magic item shops, except for the basic consumables (e.g., healing potions), and making sure there is enough treasure to be had that such things are within your price range. In a setting like Eberron it will take more finagling, and I will address that when the time comes.

This same principle holds true for other genres: if a player in a Star Wars game wants to get ahold of Boba Fett-style armor, I will find a way to make it available to them, and so forth. This may require metagame discussions to make sure the player's wishes don't interfere with the rest of the group's or throw the campaign into disarray, etc., but it is a ramification of the "I will run the game the players want to play" item from up above.

The real currency of the game is not gold pieces or experience points, it's each player's "moment to shine" at the table. As long as a player's desires don't invalidate anyone else's, there's no reason not to try to make it happen.

If it takes more than three sentences to describe your surroundings, I need to simplify.

Honestly, this is a note to myself. I tend to go purple in my room descriptions when I'm at the computer, and then regret it at the table when I find myself reading walls o' text out loud.

I will override the game system if I feel there's a compelling reason to do so.

If you're in a fight with something that has a giant bag of hit points but that cannot possibly escape its doom, I'll just say, "Fine, four rounds later it's dead," rather than make you sit there rolling dice. If we've had a long, grueling session and we all just want to call it a night, I'm not going to mess with random encounters as you trudge back to town.

I will allow group override.

Similar to the point above, if everybody agrees that something sucks, I will allow it to be altered. If everybody agrees that something would be awesome, I will let it happen. Note that "everybody" includes me.